Illumination means having light emitting elements of different wavelength emission characteristics

ABSTRACT

Illumination device, image apparatus using the device and information processing system using the apparatus for illuminating a light beam emitted from at least two light emitting elements of different light emission wavelength ranges to an original through a light conductor prevent irregularity of illumination on the original without providing compensation means to attain improvement in color discrimination ability of a color document sheet read signal without increasing a cost. A light beam applied from an illumination device 30 arranged at an end of a light conductor 3 is scattered and reflected by a scatter and reflection area 5 of the light conductor to illuminate the original 100. The illumination device 30 at least two light emitting elements 81G and 81R of different light emission wavelength ranges and centers of the light emitting elements are arranged at positions spaced from a normal line passing through a center of the scatter and reflection area 5.

This application is a continuation of application Ser. No. 08/358,096filed Dec. 16, 1994, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an illumination device, an imagereading apparatus having the illumination device and an informationprocessing system having the image reading apparatus, and moreparticularly to an information processing system such as copyingapparatus, facsimile apparatus, scanner and electronic blackboard, animage reading apparatus used therein and an illumination device suitablyused in the reading apparatus.

2. Related Background Art

In a prior art a reading apparatus of an information processing systemsuch as a facsimile machine or an electronic copying machine, adischarge lamp such as a fluorescent lamp or an LED array having anumber of LED chips in array has been used as an illumination device.Recently, as the facsimile machine is used even in home, a compact andlow cost product is required and many products use the LED arrays.

In order to improve an output image quality, a function capable ofoutputting a multi-tone image which images a color document readinformation without drop while using mono-tone image has been replacinga conventional binary image system, and an improvement of colordiscrimination ability for color image read information in an imagereading apparatus is required to cope with the future colorization.

A light source of an image reading apparatus to improve the colordiscrimination ability of the color document uses a plurality of LED'shaving a predetermined wavelength range and it is desired to emit alinear light beam from each of the LED light sources. An example of theimage reading apparatus having the illumination device which uses suchLED light sources is shown in FIGS. 1A to 1C.

FIG. 1A shows a sectional view of a photoelectric conversion elementarray of the image reading apparatus as viewed along a main scandirection, and FIG. 1B shows a side elevational view of the imagereading apparatus as viewed along arrow A shown in FIG. 1A.

In FIGS. 1A to 1C, numeral 10 denotes a light transmissive sensorsubstrate on which a plurality of photo-electric conversion elementsformed by using a thin film semiconductor layer such as amorphoussilicon or polycrystalline silicon are arranged in one dimension. Aprotective layer, not shown, is provided on the light transmissivesensor substrate 10 to protect the photo-electric conversion elements,not shown, from damage due to relative movement to an original.

The light transmissive sensor substrate 10 is packaged on a lighttransmissive packaging substrate 15 by bonding and is electricallyconnected with a drive circuit, not shown, which is also packaged, bywire bonding.

Numeral 30 denotes an illumination means (light source) which comprisesLED light sources 41R and 41G. Numeral 3 denotes a light transmissivemember such as a silica rod having a circular cross-section, numeral 4denotes an incident plane through which a light beam emitted from theillumination means 30 is applied to the light transmissive member 3, andnumeral 5 denotes a scatter and reflection area for scattering andreflecting the light beam propagated through the light transmissivemember 3 to take out of the light transmissive member 3. The scatter andreflection area 5 is formed by roughening a portion of the surface ofthe light transmissive member 3 or applying light diffusion reflectivepaint. Numeral 6 denotes a reflection plane formed at an end planeopposite to the illumination means 30 of the light transmissive member3. The reflection plane may be formed by vapor depositing a metal suchas aluminum to the surface of the end of the light transmissive member3, or applying a light diffusion reflective paint, or it may be aseparate member. A sectional shape of the light transmissive member 3 iscommonly square or rectangular.

A read position of an original 100, an arrangement position of anillumination window of the light transmissive sensor substrate 10 and anoptical axis along the array of the scatter and reflection area 5 of thelight transmissive member 3 are set such that they are in a verticalplane passing through a read position of the document sheet 100.

A light beam L emitted from the LED light sources 41G and 41R of therespective light emission wavelengths of the illumination means 30 anddirected into the light transmissive member 3 from the incident plane 4of the light transmissive member 3 repeats the reflection at an innersurface of the light transmissive member 3 and propagates therein, andreaches the opposite plane to the incident plane 4, where it is againreflected and propagates in the light transmissive member 3. While itrepeats the reflection, it reaches the scatter and reflection area 5where it is diffused and a portion I₁ thereof is emitted from an exitplane located to oppose area 5 and it passes through the lighttransmissive packaging substrate 15 and the illumination window in thelight transmissive sensor substrate 10 and irradiates the document sheet100. Another portion I₂ of the diffused light beam is directed to theexit plane obliquely so that it is totally reflected and propagates inthe light transmissive member. It repeats the propagation and finallyreaches the incident plane 4 where it is emitted out.

The light beam which irradiates the document sheet 100 is reflected bythe document sheet 100 and directed to the photo-electric conversionelements on the light transmissive sensor substrate 10 where it isphotoelectrically converted to produce an image read signal which isoutput to an external device.

FIG. 1C shows distributions G and R of document plane illumination in amain scan direction of the photo-electric conversion element array ofthe light sources 41G and 41R having the respective light emittingwavelength ranges when the image reading apparatus shown in FIGS. 1A and1B is used.

In the above example, as described above, the LED light sources 41G and41R having a plurality of light emission wavelength ranges are used asthe illumination means 30.

There are various sorts of LED light sources and they cannot begenerally discussed, but an LED chip of a surface packaging type whichattains further compaction and is convenient for packaging has beendeveloped recently. FIG. 2 shows a surface packaging type LED lightsource. In FIG. 2, numeral 81 denotes an LED chip, numeral 82 denotes asubstrate, numeral 83 denotes a reflection frame, numeral 84 denotes alight transmissive resin, and numerals 85 and 86 denote electrodesformed on a surface of the substrate 82. The size of the LED lightsource is less than 2 to 3 mm in length and less than 2 mm in height.Since the electrodes 85 and 86 are taken out via a side of the substrate82, it can be packaged by merely placing creamy solder on the printedpackaging substrate and heating (reflowing) it by a reflow oven. Thus,efficient packaging is attained. Accordingly, it is desirable to usesuch LED light source as a linear light source.

Since such LED light source has a light emission directivity as shown inFIG. 2, when a document sheet is to be illuminated by conducting,reflecting and diffusing the light by the light transmissive member 3 asshown in FIGS. 1A and 1B, the illumination distribution is not uniform,that is, the illumination is high in the area closer to the light source30 and low in other areas. Thus, it poses a problem in the uniformity ofthe illumination distribution.

This is due to the fact that the light beam obliquely emitted from theLED light source 30 is directly applied to the area 5 of the lighttransmissive member 3, scattered there and taken out of the lighttransmissive member 3.

Another problem rises in that the illumination to the document sheet ofdifferent light emission wavelength ranges has different factorsdepending on the longitudinal position of the document sheet. This isdue to the difference in the ratios of incident light beams, that is,the distributions, along the longitudinal side of the scatter andreflection area depending on the light emission wavelength range. (InFIG. 1C, solid line and broken line represent relative illuminationdistributions of green ray and red ray, respectively.)

Where special means to compensate such irregularity of illumination isto be provided, the mechanism is complicated and the cost increases.

FIG. 3 shows a perspective view of another example of the linear lightsource. The light sources 30 are arranged at the opposite ends of anelongated transparent member which is a light conductor 3.

Namely, in FIG. 3, numeral 3 denotes an elongated transparent member(light conductor), and numeral 11 denotes a direction of light emission.A cross section of the elongated transparent member 3 is constant, andit is mirror finished on a plane other than a light emitting plane. Alight is emitted from an LED chip 71 on a substrate 45 and it isdirected through an end of the elongated transparent member 3. The lightis reflected directly or by the mirror finished reflection plane so thatit is emitted out of the elongated transparent member 3. In FIG. 3, aplurality of LED chips having different light emission wavelengths areshown by an LED chip 71.

FIG. 4 shows a front view as viewed in the direction D of FIG. 3 and alight intensity distribution on an illumination plane (not shown). Asshown, a uniform light intensity is attained between a and c but a totallight intensity is low and a difference from the light intensity nearthe light source is large. Numerals 10a, 10b and 10c show sections atpoints a, b and c of the elongated transparent member 3, numerals 44a,44b and 44c denote light intensity distributions, and a hatched area(the plane excluding the light emission plane and the light incidentplane of the elongated transparent member 3) denotes a mirror finishedplane.

In FIG. 4, the light intensity distribution is shown for one of theplurality of LED chips as a representative.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an illuminationdevice which has a highly uniform illumination, is of low powerconsumption and easy to reduce the size, an image reading apparatushaving the illumination device, and an information processing systemhaving the image reading apparatus.

It is another object of the present invention to solve a problem ofirregularity of illumination which is caused when the LED light sourceis used as a light source of a linear illumination device and a problemof a large difference in illumination between a point close to the LEDlight source and a point spaced therefrom.

It is another object of the present invention to provide an illuminationdevice for directing light beam from a light emitting elements having atleast two light emission wavelength ranges to an original through alight conductor, an image reading apparatus having the illuminationdevice and an information processing system having the reading apparatuswherein the irregularity of the illumination of the document sheet isprevented without providing correction means and the colordiscrimination ability of a colored original read signal is improvedwithout increasing the cost.

It is another object of the present invention to provide an illuminationdevice for illuminating an original by scattering and reflecting a lightbeam emitted from illumination means arranged at an end of a lightconductor at a scatter and reflection area of the light conductor, saidillumination means having at least two light emitting elements ofdifferent light emission wavelength ranges, and said light emittingelements being spaced from a normal line passing through a center of thescatter and reflection area.

It is another object of the present invention to provide a readingapparatus comprising: a light transmissive member having a lightincident plane at an end and a light beam exit plane in a longitudinalplane other than said end; a light source for emitting a light beam tobe applied to said light incident plane; a photo-electric converter forreceiving a reflected light from the illuminated area of the lightemitted from said light emitting plane; an area for reflecting and/orscattering the light beam applied to said light transmissive memberprovided at a portion of said light transmissive member facing the lightbeam exit plane and along the longitudinal direction; and at least twolight emitting elements of different light emission wavelength rangeshaving centers thereof spaced from a normal line to said area.

It is another object of the present invention to provide an informationprocessing system comprising: (a) a photo-electric converter having aplurality of photo-electric conversion elements arranged to face adocument sheet image to be read; (b) an illumination device forilluminating the original; (c) transport means for transporting theoriginal; (d) an output unit for recording an image on a sheet by anelectrical signal in accordance with image information; and (e) acontroller for controlling said photo-electric conversion element, saidillumination device, said transport means and said output unit; saidillumination device including a light transmissive member having a lightincident plane at an end thereof and a light exit plane in onelongitudinal plane other than said end, a light source having at leasttwo light emitting elements of different light emission wavelengthranges provided to emit the light beam to be applied to said lightincident plane, an area for reflecting and/or scattering the light beamapplied to said light transmissive member being provided in a portion ofsaid light transmissive member facing the light beam exit plane, centersof said light emitting elements being arranged at positions spaced froma normal line to said area.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A, 1B, 1C and 3 show illumination devices with LED light sources,

FIG. 2 shows an example of the LED light source,

FIG. 4 shows an illumination distribution in the illumination device ofFIG. 3,

FIGS. 5A to 5C and 6A to 6C illustrate illumination devices according tofirst embodiment of the present invention,

FIGS. 7A to 7C show illumination devices according to second embodiment,

FIG. 8 shows a sectional view of an information processing system towhich the illumination device of the present invention is applied,

FIG. 9 shows a perspective view of an example of an ink jet recordinghead which is applicable to the information processing system of thepresent invention,

FIGS. 10 and 12 show perspective views of a recording unit using an inkjet recording system applicable to the information processing system ofthe present invention, and

FIG. 11 shows a block diagram of a configuration of the informationprocessing system of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The linear light source as the illumination device described above has alow total light intensity and is not uniform in the light intensitydistribution as described above. This is because the light from the LEDchip as the light source is not uniformly and sufficiently emitted fromthe internal of the elongated transparent member (light conductor) 3.

Thus, in the present invention, the arrangement of the light source iscarefully considered to assure the uniformity of the longitudinal lightemission characteristic regardless of the colors emitted by the lightsource.

Namely, in accordance with the present invention, an LED chip comprisingat least two light emitting elements having different light emissionwavelength ranges is arranged such that a center thereof is off a normalline passing through a center of a scatter and reflection area of alight transmissive member. Thus, a light beam which is directly appliedto the scatter and reflection area in the respective light emissionwavelength ranges decreases and an indirect light reflected in the lighttransmissive member increases accordingly. As a result, the highillumination at only the area close to the LED light source is avoidedand the longitudinal illumination of the light transmissive member isuniform.

Further, in each light emission wavelength range, since the light beamdirected to the scatter and reflection area is longitudinally uniform,the ratio of the illuminations of different light emission wavelengthranges at any longitudinal position of the original illumination can beequal.

Embodiments of the present invention are now explained in conjunctionwith the drawings.

Embodiment 1

FIG. 5 shows a preferred embodiment of the image reading apparatus ofthe present invention. FIG. 5A shows a sectional view of aphoto-electric conversion element array of the image reading apparatusas viewed along a main scan direction, and FIG. 5B shows a sectionalview of the photo-electric conversion element array of the image readingapparatus as viewed along a sub-scan direction. FIG. 5C shows a sideelevational view of the image reading apparatus as viewed along adirection A shown in FIG. 5A.

In FIGS. 5A to 5C, numeral 10 denotes a light transmissive sensorsubstrate on which a plurality of photo-electric conversion elementsformed by using a thin film semiconductor layer such as amorphoussilicon or polycrystalline silicon are arranged in one dimension. Aprotective layer, not shown, is formed on the light transmissive sensorsubstrate 10 to protect the photo-electric conversion elements, notshown, from damage by relative movement to a document sheet.

The light transmissive sensor substrate 10 is packaged on a lighttransmissive packaging substrate 15 by bonding and is electricallyconnected to a drive circuit, not shown, packaged thereon by wirebonding.

Numeral 3 denotes a light conductor made of a light transmissive memberhaving a rectangular section. Numeral 30 denotes a light source whichcomprises LED chips 81G and 81R which are light emitting elements havingdifferent light emission wavelength ranges as shown in FIG. 5C.

In the present embodiment, the LED chip 81G has a green light emissionwavelength range (center light emission wavelength 560 nm, half value 30nm) and the LED chip 81R has a red light emission wavelength range(center light emission wavelength 650 nm, half value 30 nm).

In order to reflect the light beam, a scatter and reflection area 5 isformed on a plane facing an exit area of the light beam from the lighttransmission member 3 by roughening the surface of the lighttransmissive member 3 or applying light diffusion and reflective paint.

A reflection area 6 for reflecting a light beam propagated through thelight transmissive member 3 is formed on the end plane of the lighttransmissive member 3 opposite to the light source 30. The reflectionarea 6 is formed by vapor depositing a metal such as aluminum to thesurface of the end of the light transmissive member or applying lightdiffusing and reflective paint, or it may be formed as a separatemember.

The read position of the document sheet 100, the arrangement position ofan illumination window of the light transmissive sensor substrate 10 andan optical axis along the array direction of the scatter and reflectionarea 5 of the light transmissive member 3 are set such that they are ina normal plane passing through the read position of the original 100.

Of the light beams emitted from the LED chips 81G and 81R of therespective light emission wavelength ranges of the light source 30, alight beam L directed to the scatter and reflection area 5 is scatteredand reflected by the scatter and reflection area 5 and a portion I₁ ofthe light beam goes out of the light transmissive member 3, passesthrough the light transmissive packaging substrate 15 and theillumination window the light transmissive sensor substrate 10 toilluminate the original 100, and the light beam which illuminated thedocument sheet 100 is reflected by the original 100 and directed to thephoto-electric conversion elements on the light transmissive sensorsubstrate 10 as an information light and photo-electrically convertedthereby, and output to the external as an image read signal. Anotherportion I₂ of the scattered and reflected light beam further propagatesthrough the light transmissive member 3.

In the present embodiment, centers of the LED chips 81G and 81R of therespective light emission wavelength ranges of the light source 30 aredeviated from a normal line passing through the center of the scatterand reflection area 5.

In order to simplify the explanation of an operation of the presentembodiment, a right half of FIG. 5C, that is, only the light beamemitted by the LED chip 81G is considered.

FIGS. 6A to 6C illustrate a difference between the illumination deviceof the present embodiment and other illumination devices. FIGS. 6A and6B show examples of other illumination devices, and FIG. 6C shows theright half of the embodiment of the present invention shown in FIG. 5C.

FIGS. 6A to 6C show a side elevational view of the light transmissivemember 3 and the light source 30 as viewed in the direction A shown inFIG. 5A and an illumination distribution on the document sheet planeattained when the illustrated illumination device is used.

As shown, in FIG. 6A, the light transmissive member 3 having a circularcross section is used with the center thereof coinciding with the centerof the LED chip 81 and the normal line passing through the center of thescatter and reflection area 5 passing through the center of the LED chip81. In FIG. 6B, the light transmissive member 3 has a rectangular crosssection, and a cross point of diagonal lines thereof coincides with thecenter of the LED chip 81 and the normal line passing through the centerof the area 5 passes through the center of the LED chip 81.

FIG. 6C shows the right half of the embodiment of the present invention.The light transmissive member has a rectangular cross section and thecenter of the LED chip 81 is spaced from the normal line passing throughthe widthwise center of the scatter and reflection area 5 by a distancea.

In any case, the distance from the center of the LED chip 81 and theplane of the light transmissive member on which the scatter andreflection area 5 is formed is equal to a, the LED chips 81 areidentical and they are identical to the LED chips 81G used in thepresent embodiment.

The light beam emitted from the LED chip 81 and directed to the lighttransmissive member 3 may be divided into a direct incident light whichis directly applied to the scatter and reflection area 5 without beingreflected by the internal plane of the light transmissive member 3, andan indirect incident light which is applied after at least onereflection by the internal plane.

The direct incident light is now considered. A light intensity which isdirectly applied to the scatter and reflection area 5 depends on anangle Δθ looking into the scatter and reflection area 5 from the centerof the LED chip 81. The larger Δθ is, the larger is the light intensityof the direct incident light, and the smaller it is, the smaller is thelight intensity. Assuming that a width of the scatter and reflectionarea 5 is w and a vertical distance from the center of the LED chip 81to the scatter and reflection area 5 is a, the angle Δθ is given by

    Δθ=2 tan.sup.-1 {(w/2)/a}≅w/a

because the LED light source is located immediately above the scatterand reflection area 5 in FIGS. 6A and 6B.

On the other hand, in the embodiment of the present invention shown inFIG. 6C, the LED chip 81 is located not immediately above the scatterand reflection area 5 but laterally spaced by the distance a.Accordingly, the angle Δθ is given by

    Δθ=2 tan.sup.-1 {(w/2×2.sup.1/2)/2.sup.1/2 xa}≅w/2a

which is approximately one half of that of FIGS. 6A and 6B.

Thus, in the present embodiment, the light intensity of the directincident light is reduced compared to that of the prior art.

On the other hand, the indirect incident light increases accordingly. Asa result, the illumination distribution of the document sheet isimproved as a whole because the peak near the LED light source issuppressed.

This will be readily understood from a graph of a relative illuminationversus the distance from the light source shown in FIGS. 6A to 6C. InFIGS. 6A and 6B, the peak and the light intensity of the indirectincident light at the area close to the light source are so large thatthe total light intensity of the indirect incident light and the directincident light is not uniform but has a peak closely to the lightsource. On the other hand, in the present embodiment as shown in FIG.6C, the peak of the direct incident light is reduced compared to thoseof FIGS. 6A and 6B, and the peak of the indirect incident light isdeviated away from the light source so that the total light intensity isuniform over a wide longitudinal range although it is reduced in thearea close to the light source. Namely, the usability as theillumination device is significantly improved.

The total illumination gradually decreases at the area farther from thelight source than from the peak of the indirect incident light, but itis actually compensated by the light reflected by the reflection area 6provided on the opposite side of the light source 30 shown in FIG. 5A sothat the illumination is kept uniform.

In FIG. 6C, only the right half of the present embodiment is shown. Asshown in the present embodiment of FIG. 5C, when the LED light sources41G and 41R having different light emission wavelength ranges areprovided laterally with respect to the normal line, the respective LEDlight sources operate in the same manner and the light beam emitted fromthe LED chip 81G and the light beam emitted from the LED chip 81R areuniformly directed longitudinally to the scatter and reflection area 5so that the longitudinal illumination of the document sheet is uniformfor the respective light emission wavelength range. Further, since theillumination of the document sheet of the different light emissionwavelength ranges is uniform, the ratios of illuminations of thedifferent light emission wavelength ranges at any longitudinal positionof the document sheet illumination are equal or can be made closer.

The deviation between the LED chips 81G and 81R is at least that whichassures the deviation from the normal line passing through the center ofthe scatter and reflection area 5 of the light transmissive member 3,but when the deviation is too large, most of the light beam from the LEDchip 81G or 81R are indirect light and a loss of the light beam in thelight transmissive member 3 increases. Accordingly, it should beappropriately selected. If it is extremely deviated, the illuminationdecreases at the position where the light source is located.

By arranging the light source in this manner, the high colordiscrimination ability and multi-tone output image are attained withoutproviding an illumination compensation circuit and a high quality colorread signal is produced and a low cost and compact informationprocessing system is provided.

In the present embodiment, while the light source comprises a pair ofLED light sources having the different light emission wavelength ranges,the present invention is not limited thereto. The light source maycomprise at least two light sources having different light emissionwavelength ranges with the center of the LED chip of the light sourcebeing deviated from the normal line passing through the center of thescatter and reflection area so that the light intensity directed to thescatter and reflection area is uniform. For example, in the presentembodiment, a light source which uses an LED chip having a blue lightemission wavelength range (center light emission wavelength 470 nm, halfwidth 70 nm) may be added and a plurality of LED chips of the respectivelight emission wavelength ranges may be arranged. In this manner, ahigher fidelity color documents sheet read signal to produce a colorimage can be produced at a low cost.

Embodiment 2

Referring to FIGS. 7A to 7C, a second embodiment of the presentinvention is now explained.

FIGS. 7A to 7C show the second embodiment of the present invention. FIG.7A shows a sectional view of the photo-electric conversion element arrayof the image reading apparatus as viewed along the main scan direction,and FIG. 7B shows sectional view of the photo-electric conversionelement array of the image reading apparatus as viewed along thesub-scan direction. FIG. 7C shows a side elevational view of the imagerecording apparatus as viewed in the direction A shown in FIG. 7A.

FIGS. 7A to 7C correspond to FIGS. 5A to 5C of the Embodiment 1 of thepresent invention, and the like elements in FIGS. 7A to 7C to thoseshown in FIGS. 5A to 5C are designated by the like numerals.

In FIGS. 7A to 7C, like in the Embodiment 1, numeral 10 denotes a lighttransmissive sensor substrate, numeral 15 denotes a light transmissivepackaging substrate and numeral 3 denotes a light conductor having arectangular cross section. Like in the Embodiment 1, a light source 30is formed closer to a light beam incident plane 4 and a reflection area6 is formed on the opposite side.

Like in the Embodiment 1, the read position of the document sheet 100,the arrangement position of the illumination window of the lighttransmissive sensor substrate 10 and the optical axis along the arraydirection of the scatter and reflection area 5 of the light transmissivemember 3 are set such that they are in the normal plane passing throughthe read position of the document sheet 100.

As shown in FIG. 7C, in the present embodiment, the LED chips 81G and81R of different light emission wavelength ranges of the light source 30are arranged symmetrically and normally to the normal line passingthrough the center of the scatter and reflection area 5 with a spacingtherefrom.

Like in the Embodiment 1, in the present embodiment, the LED chips 81Gand 81R of the respective light emission wavelength ranges of the lightsource 30 are deviated from the normal line passing through the centerof the scatter and reflection area 5 so that the document sheetillumination of the respective light emission wavelength ranges isuniform. In the present embodiment, the centers of the LED chips 81G and81R of the respective light emission wavelength ranges of the lightsource 30 are arranged symmetrically and normally to the normal linepassing through the center of the scatter and reflection area 5 with thespace therefrom. Accordingly, the light beams directly applied to thescatter and reflection area 5 from the LED chips 81G and 81R can beapplied at the same efficiency longitudinally and the document sheetillumination distributions of different light emission wavelength rangesare attained at the same distribution. Thus, the high quality colordocument sheet read signals in the respective light emission wavelengthranges are produced and a low cost and compact information processingsystem is provided.

In any embodiment, the light sources 30 may be arranged at the oppositeends of the light transmissive member 3 and the types of the lightemitting light sources at the opposite ends may not be identical. Forexample, when the light emission intensity of one of the red (R), green(G) and blue (B) is low, the low one may be arranged at the oppositeside and the other may be arranged on the end planes to adjust the lightintensity.

When required, the light intensity may be adjusted through a filter.

An embodiment of an information processing system to which theillumination device of the present invention is applied is nowexplained.

FIG. 8 shows an information processing apparatus (for example afacsimile machine) constructed by using the photo-electric conversiondevice of the present invention.

Numeral 102 denotes a feed roller for feeding a document sheet 17 towarda read position, numeral 104 denotes a separator for separating andfeeding the document sheet P one at a time, and numeral 18 denotes atransport roller provided at the read position of the photo-electricconversion device 100 for defining a read plane of the document sheet 17and transporting the document sheet 17.

W denotes a recording medium in the form of a rolled sheet on whichimage information read by the photo-electric conversion device 100, orimage signal externally transmitted in the case of the facsimile machineis formed. Numeral 110 denotes a recording head for forming the imageand it may be a thermal head, an ink jet recording head or other head.The recording head may be either serial type or line type. Numeral 112denotes a platen controller for transporting the recording medium W tothe recording position of the recording head 110 and defining the recordplane.

Numeral 120 denotes a console panel having switches for operation inputsand a display for displaying a message and a state of the devicearranged therein.

Numeral 130 denotes a system control board on which a control unit forcontrolling the respective units, a drive circuit of the photo-electricconversion elements, a processing unit for the image information and atransmitter/receiver unit are arranged. Numeral 140 denotes a powersupply of the device.

The output method applicable to the information processing system shownin FIG. 8 includes a thermal transfer recording method using a thermalhead and an ink jet recording method using an ink jet recording head.

A configuration when the recording head of this type is connected to theoutput unit of the information processing system as the output means isnow explained. Only the output unit is explained here.

Of the ink jet recording system, the recording head using the thermalenergy provides a better effect to the present invention because theeffect of the compaction of the illumination device is reflected to theentire information processing system as the head itself can be compact.

The typical construction and the operational principles are preferablythe ones disclosed in U.S. Pat. No. 4,723,129 and U.S. Pat. No.4,740,796. The principle and the structure are applicable to so-calledon-demand type recording systems and continuous type recording systems,but the on-demand type is suitable because it permits the reduction ofthe size.

This system is briefly explained. At least one driving signal is appliedto an electro-thermal transducer disposed on a liquid (ink) retainingsheet or liquid passage, the driving signal being large enough toprovide such a quick temperature rise beyond a departure from nucleationboiling point, by which the thermal energy is provided by theelectro-thermal transducer to produce film boiling on the heatingportion of the recording head, whereby a bubble can be formed in theliquid (ink) corresponding to each of the driving signals. By thegeneration, development and contraction of the bubbles, the liquid (ink)is ejected through a discharge port to produce at least one droplet. Thedriving signal is preferably in the form of pulse because thedevelopment and the contraction of the bubbles can be effectedinstantaneously, and therefore the liquid (ink) is ejected with fastresponse.

The driving signal is preferably such as those disclosed in U.S. Pat.No. 4,463,359 and U.S. Pat. No. 4,345,262. In addition, the temperaturerise rate of the heating surface is preferably such as those disclosedin U.S. Pat. No. 4,313,124.

The structure of the recording head may be those shown in U.S. Pat. No.4,558,333 and U.S. Pat. No. 4,459,600 in which the heating portion isdisposed at a bent portion, as well as the structure of the combinationof the ejection outlet, liquid passage and the electro-thermaltransducer disclosed in the above-mentioned patents.

In addition, the present invention is applicable to the structuredisclosed in Japanese Laid-Open Patent Application No. 59-123670 inwhich a common slit is used as the discharge port for a plurality ofelectro-thermal transducers, and the structure disclosed in JapaneseLaid-Open Patent Application No. 59-138461 in which an opening forabsorbing a pressure wave of thermal energy is formed corresponding tothe discharge port.

The present invention is effectively applicable to a so-called full-linetype recording head having a length corresponding to the maximumrecording width. Such a recording head may be comprised of a singlerecording head and plural recording head combined to cover the maximumwidth.

In addition, the present invention is applicable to a serial typerecording head in which the recording head is fixed on a main assembly,to a replaceable chip type recording head which is connectedelectrically with the apparatus and can be supplied with the ink when itis mounted in the main assembly, or to a cartridge type recording headhaving an integral ink container.

The provision of the recovery means and/or the auxiliary means for thepreliminary operation are preferable because they further stabilize theeffects of the present invention.

As for such means, there are capping means for the recording head,cleaning means therefor, pressing or sucking means, preliminary heatingmeans which may be an electro-thermal transducer, an additional heatingelement or a combination thereof. Also, means for effecting preliminarydischarge (not for the recording) may stabilize the recording operation.

Further, as a recording mode, the present invention is effectivelyapplicable to an apparatus having at least one of a monochromatic modemainly with black, a multi-color mode with different color inks and/orfull color mode using the mixture of colors.

Furthermore, in the foregoing embodiment, the ink is liquid.Alternatively, ink which is solidified below a room temperature andliquefied at a room temperature may be used. Since the ink is controlledwithin a temperature range of not lower than 30° C. and not higher than70° C. to stabilize the viscosity of the ink to provide the stabledischarge in a conventional recording apparatus of this type, the inkmay be such that it is liquid within the temperature range when therecording signal is applied. The present invention is applicable toother types of ink. In one of them, the temperature rise due to thethermal energy is positively prevented by consuming it for the statechange of the ink from the solid state to the liquid state. Other ink issolidified when it is left, to prevent the evaporation of the ink. Inany case, the application of the recording signal producing thermalenergy, the ink is liquefied, and the liquefied ink may be discharged.Other ink may start to be solidified at the time when it reaches therecording sheet. The present invention is also applicable to the inkwhich is liquefied by the application of the thermal energy.

A system in which the recording is made by discharging the liquid byutilizing the thermal energy is now explained briefly.

FIG. 9 shows a construction of an ink Jet recording head which comprisesan electro-thermal transducer 1103, an electrode 1104, a liquid path1105 and a top plate 1106 formed on a substrate 1102 through asemiconductor manufacturing process such as etching, vapor depositionand sputtering. Recording liquid 1112 is supplied from a liquid storage,not shown to a common liquid chamber 1108 of the recording head 1101through a liquid supply tube 1107. Numeral 1109 denotes a liquid supplytube connector.

The liquid supplied to the common liquid chamber 1108 is supplied to theliquid path 1110 by a capillary phenomenon and forms a meniscus on thedischarge port (orifice) at the end of the liquid path so that it isheld stably. By energizing the electro-thermal transducer 1103, theliquid on the electro-thermal transducer is abruptly heated and airbubbles are created in the liquid path. By the expansion and thecontraction of the air bubbles, the liquid is discharged from thedischarge port 1111 to form droplets.

By this arrangement, a full line type ink jet head having 128 or 256discharge ports arranged at a high discharge port density of 16nozzles/mm, or even over the entire recording width can be provided.

FIG. 10 shows a perspective view of an external construction of anoutput unit using the ink jet recording system.

In FIG. 10, numeral 1801 denotes an ink jet recording head whichdischarges the ink in accordance with a predetermined record signal torecord a predetermined image, and numeral 1802 denotes a carriage forscanning the recording head 1801 along the recording direction (mainscan direction). The carriage 1802 is slidably supported by guide shafts1803 and 1804 and reciprocally driven along the main scan direction by atiming belt 1808. The timing belt 1808 which engages with pulleys 1806and 1807 is driven by a carriage motor 1805 through the pulley 1807.

A recording sheet 1809 is guided by a paper ban 1810 and transported bya sheet feed roller, not shown, pinched by a pinch roller.

The transport is conducted by a sheet feed motor 1816 as a drive source.The transported record sheet 1809 is tensioned by a sheet ejectionroller 1813 and a spur 1814 and it is transported while it is contactedto a heater 1811 by a retainer plate 1812 made of a resilient member.The record sheet 1809 on which the ink discharged by the recording headis deposited is heated by the heater 1811 and the water of the depositedink is evaporated and the ink is fixed to the record sheet 1809.

Numeral 1815 denotes a unit called a recovery unit which eliminatesforeign material deposited on the discharge port (not shown) of therecording head 1801 and the ink of high viscosity to maintain the normaldischarge characteristics.

Numeral 1818a denotes a cap which is a portion of the recovery unit 1815and caps the discharge port of the recording head 1801 to prevent theclogging. An ink absorber is preferably arranged in the cap 1818a.

A blade 1817 for cleaning the foreign material and ink deposited on thedischarge port is provided on the side of the recovery unit 1815 facingthe record area to abut against the plane on which the discharge port ofthe recording head 1801 is formed.

In the present invention, as shown in a block diagram of FIG. 11, thedocument sheet fed to the read unit of the read device 2000 by thedocument sheet transport means 2007 is read by the photo-electricconversion element 2001 of the read device 2000, and an electricalsignal bearing the image signal is converted to an electrical signal byimage processing means (not shown) for recording, and a controller suchas a CPU 2002 controls the carriage motor 2003, the recording head 2004,the sheet feed motor 2005 and the recovery unit 2006 for recording.

The electrical signal bearing the image information may be transmittedto another image processing apparatus through communication means 2008and output therefrom, or another information processing system mayreceive the information through the communication means 2008 to conductthe recording by the recording head 2004.

FIG. 12 shows an output unit when a full line type recording head 1932is mounted.

In FIG. 12, numeral 1965 denotes a feed belt for transporting the recordmedium and transports the record medium, not shown, as the transportroller 1964 is rotated. The bottom plane of the recording head 1932 isthe discharge port plane 1931 having a plurality of discharge portsarranged for the recording area of the recording medium.

In this arrangement, the same recording as that by the serial type headis attained.

The above output unit is illustrative and many modifications thereof maybe made.

However, when the system for discharging the liquid by utilizing thethermal energy is used, more compaction is attained and finer recordingis attained. Thus, the advantage of the present invention is moreeffectively utilized and an excellent information processing system isprovided.

As described above, according to the present invention, an illuminationdevice which is compact and attains uniform illumination at a highintensity is provided.

The present invention further provides an illumination device which issimple in construction and simple in manufacturing process.

The present invention further provides a photoelectric conversionapparatus and an information processing system which can stably read animage.

The present invention further provides the mounting of the light sourcein a simple process and a simple method.

The present invention further provides a linear light source having lessirregularity of light intensity on the illumination plane to reduce aburden in processing the image and attain high tonality.

The present invention may be modified or changed without departing fromthe scope of the invention and the embodiments described above may beappropriately combined.

In accordance with the present invention, at least two LED chips havingdifferent light emission wavelength ranges are spaced from the normalline passing through the center of the scatter and reflection area ofthe light transmissive member. Thus, the light beam directly applied tothe scatter and reflection area in the respective light emissionwavelength range is decreased and the indirect light reflected in thelight transmissive member is increased accordingly so that the increaseof the illumination in the area close to the LED light source is avoidedand the longitudinal illumination of the light transmissive member isuniform, and the ratios of the illuminations of the respective lightemission wavelength ranges at any longitudinal position of the documentsheet illumination are equal.

In accordance with the present invention, the read signal of the colordocument sheet is uniform without providing an illumination compensationcircuit, and an information processing system suitable for reading thecolor document sheet is provided without increasing the cost.

What is claimed is:
 1. An illumination device for illuminating anoriginal by reflecting a light beam emitted from an illumination means,arranged at an end of a light conductor, the light beam being reflectedat a reflection area of said light conductor, the reflection area beingarranged at a part of said light conductor, and said illumination meanscomprising at least two light emitting elements of different lightemission wavelength ranges,wherein a center of one of said lightemitting elements is deviated in a widthwise direction from a normalline passing through a center of the reflection area when viewed in alongitudinal direction of said light conductor.
 2. An illuminationdevice according to claim 1, wherein said light emitting elements arearranged symmetrically to the normal line passing through the center ofthe scatter and reflection area at positions spaced from the normal lineby equal distances from the scatter and reflection area.
 3. Anillumination device according to claim 1 wherein said at least two lightemitting elements of different light emission wavelength ranges areLED's.
 4. An illumination device according to claim 1, wherein thescatter and reflection area of the light conductor is formed along alongitudinal direction of the light conductor, the illumination means isarranged at an end of the longitudinal direction of the light conductor,and reflection means is formed at a second end of the light conductor.5. An illumination device according to claim 1 wherein said area isformed by light reflective paint.
 6. An illumination device according toclaim 1 wherein said area is a roughened surface.
 7. An illuminationdevice according to claim 1, wherein the at least two light emittingelements emit at least a green light wavelength range and a red lightemission wavelength range, respectively.
 8. An illumination deviceaccording to claim 1, wherein the light emitting elements of differentwavelength ranges have at least different intensities, respectively. 9.An illumination device according to claim 1, wherein the illuminationmeans is provided at the end of the light conductor.
 10. An illuminationdevice according to claim 1, wherein the illumination means are providedat the end and a second end of the light conductor.
 11. An illuminationdevice according to claim 1, wherein the illumination means is providedat the end of the light conductor, and a reflection means is provided ata second end of the light conductor.
 12. An illumination deviceaccording to claim 1, wherein said illumination means is arranged at thelongitudinal end of the light conductor.
 13. An illumination devicecomprising:(a) a plurality of light sources each having different lightemission wavelength ranges, placed at a part of a light guide; and (b) areflection portion, arranged at a part of said light guide, forreflecting light emitted by said plurality of light sources, wherein anormal line passing through a center of a width of the reflectionportion deviates in a widthwise direction from a center of one of saidplurality of light sources, when viewed from a longitudinal direction ofsaid light guide.
 14. An illumination device according to claim 13,wherein said plurality of light sources comprise a plurality of lightemitting diodes.
 15. An illumination device according to claim 13,wherein said reflection portion is formed along a longitudinal directionof said illumination device, wherein said plurality of light sources isarranged at a first end of the longitudinal direction of saidillumination device, and wherein said reflection portion is formed at asecond end of said illumination device.
 16. An illumination deviceaccording to claim 13, wherein said reflection portion is formed bylight reflective paint.
 17. An illumination device according to claim13, wherein said reflection portion comprises a roughened surface. 18.An illumination device according to claim 13, wherein one of saidplurality of light sources emits light in at least a green lightwavelength range and another of said plurality of light sources emitslight in at least a red light wavelength range.
 19. An illuminationdevice according to claim 13, wherein said plurality of light sources isprovided at a first end of said illumination device, and wherein saidreflection portion is provided at a second end of said illuminationdevice.
 20. An illumination device for illuminating an original byreflecting a light beam emitted from illumination means, arranged at alongitudinal end of a light conductor, the light beam being reflected ata reflection area of said light conductor, the reflection area beingarranged at a part of said light conductor,wherein the illuminationmeans comprises at least two light emitting elements of different lightemission wavelength ranges, and wherein a line passing through a centerof one of said at least two light emitting elements is deviated in awidthwise direction from a normal line passing through a center of awidth of the reflection area.
 21. An illumination device comprising:(a)a plurality of light sources each having different light emissionwavelength ranges, placed at a part of a light guide; (b) a reflectionportion, arranged at a part of the light guide, for reflecting lightemitted by said plurality of light sources, wherein a normal linepassing through a center of a width of said reflection portion deviatesin a widthwise direction from a light beam axis of one of said pluralityof light sources, when viewed in the direction of the light beam axis.22. An illumination device according to claim 21, wherein said pluralityof light sources comprise a plurality of light emitting diodes.
 23. Anillumination device according to claim 21, wherein said reflectionportion is formed along a longitudinal direction of said illuminationdevice, wherein said plurality of light sources is arranged at a firstend of the longitudinal direction of said illumination device, andwherein said reflection portion is formed at a second end of saidillumination device.
 24. An illumination device according to claim 21,wherein said reflection portion is formed by light reflective paint. 25.An illumination device according to claim 21, wherein said reflectionportion comprises a roughened surface.
 26. An illumination deviceaccording to claim 21, wherein one of said plurality of light sourcesemits light in at least a green light wavelength range and another ofsaid plurality of light sources emits light in at least a red lightwavelength range.
 27. An illumination device according to claim 21,wherein said plurality of light sources is provided at a first end ofsaid illumination device, and wherein said reflection portion isprovided at a second end of said illumination device.
 28. Anillumination device comprising:(a) a plurality of light sources eachhaving different light emission colors, placed at a part of a lightguide; and (b) a reflection portion, arranged at a part of said lightguide, for reflecting light emitted by said plurality of light sources,wherein a normal line passing through a center of a width of thereflection portion deviates in a widthwise direction from a center ofone of said plurality of light sources, when viewed from a longitudinaldirection of the light guide.
 29. An illumination device according toclaim 28, wherein said plurality of light sources comprise a pluralityof light emitting diodes.
 30. An illumination device according to claim28, wherein the reflection portion is formed along a longitudinaldirection of said illumination device, wherein said plurality of lightsources is arranged at a first end of the longitudinal direction of saidillumination device, and wherein the reflection portion is formed at asecond end of said illumination device.
 31. An illumination deviceaccording to claim 28, wherein the reflection portion is formed bylight-reflective paint.
 32. An illumination device according to claim28, wherein the reflection portion comprises a roughened surface.
 33. Anillumination device according to claim 28, wherein one of said pluralityof light sources emits green light and another of said plurality oflight sources emits red light.
 34. An illumination device according toclaim 28, wherein said plurality of light sources is provided at a firstend of said illumination device, and wherein the reflection portion isprovided at a second end of said illumination device.
 35. Anillumination device comprising:(a) a plurality of light sources eachhaving different light emission ranges arranged at a longitudinal end ofa light guide; (b) a reflection portion, arranged at a part of saidlight guide, for reflecting light emitted by said plurality of lightsources,wherein a line passing through a center of one of said pluralityof light sources is deviated in a widthwise direction from a normal linepassing through a center of a width of the reflection portion.
 36. Anillumination device according to claim 35, wherein said plurality oflight sources comprise a plurality of light emitting diodes.
 37. Anillumination device according to claim 35, wherein the reflectionportion is formed along a longitudinal direction of said illuminationdevice, wherein said plurality of light sources is arranged at a firstend of the longitudinal direction of said illumination device, andwherein the reflection portion is formed at a second end of saidillumination device.
 38. An illumination device according to claim 35,wherein the reflection portion is formed by light-reflective paint. 39.An illumination device according to claim 35, wherein the reflectionportion comprises a roughened surface.
 40. An illumination deviceaccording to claim 35, wherein one of said plurality of light sourcesemits green light and another of said plurality of light sources emitsred light.
 41. An illumination device according to claim 35, whereinsaid plurality of light sources is provided at a first end of saidillumination device, and wherein the reflection portion is provided at asecond end of said illumination device.
 42. An illumination deviceaccording to claims 21 or 35, wherein the normal line passing throughthe center of the width of the reflection portion deviates in thewidthwise direction from a parallel plane including a light beam axiswhen viewed in the direction of the light beam axis.
 43. An illuminationdevice according to claims 13, 21, 28, or 35, wherein said plurality oflight sources are arranged at a longitudinal end of said light guide.44. An illumination device for illuminating an original by reflecting alight beam emitted from illumination means, arranged at a longitudinalend of a light conductor, the light beam being reflected at a reflectionarea of the light conductor, the reflection area being arranged at apart of said light conductor,wherein said illumination means comprisesat least two light emitting elements of different light emissionwavelength ranges, and wherein a center of one of said at least lightemitting elements is deviated in a widthwise direction from a normalplane extending in the longitudinal direction and passing through acenter of a width of the reflection area.
 45. An illumination deviceaccording to claims 20 or 44, wherein the longitudinal direction is amain scan direction and the widthwise direction is a sub-scan direction.46. An illumination device according to claims 20 or 44, wherein anormal plane passing through the center of the width of the reflectionarea passes through a read position of the original.
 47. An illuminationdevice for illuminating an original by reflecting a light beam emittedfrom illumination means, arranged at a longitudinal end of a lightconductor, the light beam being reflected at a reflection area of saidlight conductor, the reflection area being arranged at a part of thelight conductor,wherein the illumination means comprises at least twolight emitting elements of different light emission wavelength ranges,and wherein a center of one of the light emitting elements is deviatedfrom a normal line passing through a center of the width of thereflection area in a widthwise direction when viewed from a longitudinaldirection of said light conductor.
 48. An illumination devicecomprising:a plurality of light sources each having different lightemission colors; and a longitudinal light guide, for guiding lightintroduced from a plurality of light sources and for emitting the lightalong a longitudinal side thereof, having a longitudinal reflectionmember arranged along said light guide for reflecting the light fromsaid plurality of light sources, wherein at least at an end of saidreflection member near said plurality of light sources, a normal linepassing through a center of a width of said reflection member is shiftedfrom a center of at least one of said plurality of light sources, whenviewed from a longitudinal direction of said light guide.
 49. A deviceaccording to claim 48, wherein said reflection member includeslight-reflecting paint.
 50. A device according to claim 48, wherein saidreflection member includes a coarse surface.
 51. An illumination devicecomprising:a longitudinal surface that extends in a longitudinaldirection of a light guide; an end surface disposed at one longitudinalend of said longitudinal surface; a plurality of light sources disposedon the end surface, the plurality of light sources each having differentlight emission colors; and a longitudinal reflection member disposed onthe longitudinal surface, a reflection member normal line that passesthrough a center of a width of said longitudinal reflection member beingshifted, at least at an end of said longitudinal reflection member nearthe end surface, from a center of at least one of said plurality oflight sources when viewed from a longitudinal direction of said lightguide.
 52. A device according to claim 51, wherein said reflectionmember includes light-reflecting paint.
 53. A device according to claim51, wherein said reflection member includes a coarse surface.
 54. Anillumination device comprising:a longitudinal surface that extends in alongitudinal direction of said light guide; an end surface disposed atone longitudinal end of the longitudinal surface; a longitudinalreflection member disposed on the longitudinal surface; and a pluralityof light sources each having different light emission colors disposed onthe end surface, at least one said plurality of light sources beingshifted from a normal plane that passes through a center of a width ofsaid longitudinal reflection member.
 55. A device according to claim 54,wherein said reflection member includes light-reflecting paint.
 56. Adevice according to claim 54, wherein said reflection member includes acoarse surface.